Visualization of sound field and sound source vibration using laser measurement method

Visualizations help us to understand the sound field behavior. A well-known method of sound field visualization is Kunt’s experiment which visualizes standing waves using light particles. Comprehending of both accurate and transient information on sound fields requires measurement of information at multiple points, and also their visualization. Microphones are commonly used to implement such measurements, which means that numerous microphones are needed. On the other hand, Laser Doppler Vibrometer (LDV) can be used to measure an average sound pressure over a laser path. We have conducted fundamental research on sound field measurement and visualization using LDV and Computed Tomography (CT) without ordinary microphones. The measured value contains integrated information on the laser path. If we have data on an area measured from all directions using LDV, we can estimate the sound field in the area without having to measure at many points using microphones. The new technology of observing sound field and vibration is proposed and being put to practical use in this way. The sound field is generated by sound source and it is important to know the relationship between sound field and sound source. It is very useful to observe both sound field and sound source vibration simultaneously. In this paper, we describe the integrated visualization of sound field and sound source vibration using 3D laser measurement method. We used Processing programming language in order to realize the interactive visualization of sound field and sound source vibration. In addition, we conducted an experimental measurement of impulse responses with laser CT and Time Stretched Pulse (TSP) signal.